Method and system for bioremediation of hydrocarbon contaminated water

Abstract

A method and reactor for decontaminating underground aqueous plumes containing gasoline or other petroleum-derived hydrocarbons. The reactor contains a solid, non-sorptive packing, e.g a stainless steel foraminous packing which is characterized by a free space of at least 75%. The packing carries a microbial heterogeneous population derived from soil indigenous microbial community. The contaminated stream is passed through the bed in microaemphilic conditions. The performance of the process is better than that of a comparable process and apparatus using granulated peat moss.

We claim:  
     
       1. An in-situ reactor for at least partially biodegrading petroleum-derived hydrocarbons present in an underground aqueous mixture or stream, said reactor comprising: 
       a chamber disposed underground, devoid of pumping equipment and having:  
       an inlet adapted to allow a flow by natural hydraulic gradient of a contaminated mixture or stream through the chamber and an outlet for a treated mixture or stream,  
       a volume of a solid, substantially rigid, non-sorptive packing in said chamber, said packing disposed to leave a free space of at least 75%, and  
       an amount of microorganisms disposed on and within said packing, said microorganisms effective to at least partially biodegrade said hydrocarbons from said mixture or stream.  
     
     
       2. The reactor according to claim  1  wherein said packing is corrosion resistant. 
     
     
       3. The reactor according to claim  2  wherein said packing is of stainless steel. 
     
     
       4. The reactor according to claim  1  wherein said packing is composed of perforated separable pieces. 
     
     
       5. A method of at least partially biodegrading petroleum derived hydrocarbons present in an underground aqueous mixture or stream, the method comprising 
       supporting a population of microorganisms specific to petroleum-derived hydrocarbons on and within a substrate packing confined in a chamber devoid of pumping equipment, disposed underground in the path of an underground stream to be treated, the chamber configured to allow said mixture or stream to flow therethrough by natural hydraulic gradient, such that said stream contacts said microorganisms, and  
       allowing said aqueous stream or mixture to pass through said packing by natural hydraulic gradient such that said microorganisms decompose at least partly said hydrocarbons in said mixture or stream as it flows through said packing,  
       wherein said packing comprises solid, substantially rigid non-sorptive elements which leave a free space of at least 75%.  
     
     
       6. The method of claim  5  further comprising maintaining predominantly microaerophilic conditions in said mixture or stream during its passing through said packing. 
     
     
       7. The method according to claim  5  wherein said microorganism population is heterogenous, mixed microbial population originated from indigenous soil microbial community.